Carbonate synthesis from alkylene carbonates

ABSTRACT

R-OOC-O-R   ARE MADE BY REACTING AN ALKYLENE CARBONATE HAVING THE FORMULA   2-(O=),4-R1-1,3-DIOXOLANE   WITH A NON-TERTIARY HYDROXY-CONTAINING COMPOUND HAVING THE FORMULA   R-OH   WHILE IN THE PRESENCE OF A CATALYTIC AMOUNT OF AN ALKALI METAL OR A DERIVATIVE THEREOF WHEREIN R IS AN ALKYL OR ALKOXYALKYL AND R1 IS H, ALKYL OR ALKOXYALKYL. THESE CARBONATES ARE USEFUL AS SYNTHETIC LUBRICANTS, SOLVENTS FOR CELLULOSIC COMPOUNDS, E.G. CULLULOSIC ETHERS, AND IN LACQUER FIXATION. CARBONATES HAVING THE FORMULA

United States Patent US. Cl. 260463 9 Claims ABSTRACT OF THE DISCLOSURE Carbonates having the formula RO-("l-o-R are made by reacting an alkylene carbonate having the formula with a non-tertiary hydroxy-conta-ining compound having the formula ROH while in the presence of a catalytic amount of an alkali metal or a derivative thereof wherein R is an alkyl or alkoxyalkyl and R is H, alkyl or alkoxyalkyl. These carbonates are useful as synthetic lubricants, solvents for cellulosic compounds, e.g. cellulosic ethers, and in lacquer fixation.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION A process for producing carbonates having the formula has now been discovered. The use of this process avoids phosgene as a starting material and, in general, results in a clean reaction product involving little processing difficulties.

This new process comprises contacting an alkylene carbonate having the formula tat-4H1.

with a non-tertiary hydroxy-containing compound having the formula 3,642,858 Patented Feb. 15, 1972 "ice while in the presence of a catalytic amount of an alkali metal or a derivative thereof. In each of the formulas herein, each R independently is alkyl or alkoxyalkyl and R is H, alkyl or alkoxyalkyl.

In order to practice the invention, a hydroxy-containing compound having the formula ROH is contacted, in any convenient manner, with an alkylene carbonate having the formula 0 #5 r HC-(|)R1 H H while in the presence of a catalytic amount of an alkali metal or a basic derivative thereof. Typically, the reaction is conducted in a sealed or coil reactor. After reaction, usually in 0.2-24 hours, the catalyst is preferably neutralized with a strong acid, e.g. hydrogen chloride and the desired carbonate is separated from the reaction mixture by conventional techniques, e.g. fractional distillation. The major by-product of this reaction is a glycol Thus, typical alkylene carbonates useful as starting materials include ethylene carbonate, the 1,2-alk'ylene carbonates and the alkoxyalkyl-substituted ethylene carbonates. Preferred carbonates are those having an R group containing up to about ten carbon atoms; most preferred are those containing up to about six carbon atoms. Included Within the preferred 1,2-alkylene carbonates, are 1,2rpropylene carbonate, 1,2-butylene carbonate, 1,2-pentylenecarbonate, 1,2-hexylene carbonate, l,2-octylene cabonate, 1,2-dodecylene carbonate, 3-rnethyl-l,2- butylene carbonate, 3-methyl-1,2-pentylene carbonate, 3-ethyl-l,2-pentylene carbonate, 4 methyl-1,2-pentylene carbonate, 5-methyl-l,2-hexylene carbonate and the like. Included within the preferred alkoxy'alkyl-substituted ethylene carbonates are 3-methoxy-l,2-propylene carbonate, 3-ethoxy-l,2-propylene carbonate, 3-n-propoxy-l,2-pro pylene carbonate, 4-methoxy- 1,2-butylene carbonate, 4-ethoxy-l,2-butylene carbonate, S-methoxy-LZ-butylene carbonate, 5-methoxy-l,2-heptylene carbonate and the like.

Typical non-tertiary hydroxy-containing compounds useful as starting materials include the non-tertiary alkanols, e.g. those having up to about twelve carbon atoms and preferably up to about six carbon atoms, and the non-tertiary alkoxy alkanols, e.g. those having up to about ten carbon atoms and preferably up to about six carbon atoms. Thus, the preferred R groups are those having up to about twelve carbon atoms and most preferred are those having up to about six carbon atoms. Typical alkanol starting materials are methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, n-dodecanol, n-octanol and the like. Typical alkoxyalkanol starting materials include 2-methoxyethanol, 2 ethoxyethanol, 3 methoxy-n-propanol, 3- ethoxy n propanol, 4-methoxy-n-butanol, 2-ethoxynbutanol, S-methoxy-n-butanol, n-propoxyethanol and the like.

Included within the carbonates produced by this process are the alkyl carbonates, e.g. dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-n-butyl carbonate, di-n-octyl carbonate, di-isopentyl carbonate and the like and the alkoxyalkyl carbonates, e.g. bis(methoxyethyl) carbonate, bis(2-methoxypropyl) carbonate, bis- (Z-ethoxyethyl) carbonate, bis(2-n-propoxyethyl) carbonate, bis(3-methoxypropyl) carbonate and the like.

Of course, when two difierent types of hydroxy-containing compounds are used in the process of the invention, the carbonate products will not only include the symmetrical carbonates corresponding to the two types of hydroxy-containing compounds employed, but will, in addition contain the unsymmetrical carbonate. For example, a mixture of methanol and ethanol will produce ized to 1500 p.s.i. with nitrogen. The bomb was then rocked and kept at reaction temperature for a specified time.

After this time, the bomb was cooled and vented and the glass ampoule was opened and allowed to warm to room temperature. The reaction products were then analyzed by gas chromatography and nuclear magnetic resonance.

Special reactions and their conditions are reported in the table below. The reaction temperature, except where otherwise indicated, was 200 C.

TABLE Catalyst Reactants, millimoles Amt, Product, weight percent of total Type mg Hydroxy-compound Carbonate mixture NaOCHg 26 Methanol 82. 6 1,2-p1-opylene carbonate, 17. 9 Dimethyl carbonate. 13

NaOCHzCHa 1O 51.1 Ethylene carbonate 11.2 Diethyl carbonate. 18

NaOCHzCH; 14 224 1,2-propylene carbonate. 52.2 do 3 NaOCHzCH; 31 171 do 13 NaOCHiCHa 7 13 NaOCHzCHa 14 l3. l3

NaO CH2CH3 47 18. 12

NaOCHzCH; 19 12. I2

NuOH 38. 13

NaaCOa 50 38. 13

NaOAc 76 ..do d 26. 13

NHOCHZCHJ 20 n-Propanol 103 do.. 22.0 Di-n-propyl carbonate 9 NaOCHaCHz 49 Isopropanol 171 .do 50. 7 Dl-isopropyl carbonate 5 NaOCHzCH; 63 rrButanol 77. 8 .,do.. 27.0 Di-n-butyl carbonate 15 NaOCHzCH; 24 Z-methoxyethanol. 137 do.. 33.0 Bist2-rnethoxyethyl) carb0nate 10 NaOCHzCHa 21 Ethanol 125 do 23. 4 Diethyl carbonate 13 1 Reaction Temperature was 105 0.

some dimethyl carbonate, some diethyl carbonate and some methyl ethyl carbonate.

The catalysts used in this invention are the alkali metals and their basic derivatives. Thus, typical catalysts include lithium, sodium, potassium, rubidium, cesium and their hydrides, hydroxides, alcoholates, amides and the like; and the alkali metal salts formed from weak acids, e.g. acetates, carbonates, bicarbonates and the like.

The molar ratio of reactants can vary, but in general, it is preferred to use a molar excess of hydroxy-containing compound. For example, a molar ratio of hydroxycontaining compound to alkylene carbonate of at least 2/1 is preferred. Typically a catalytic amount of the alkali metals or their derivatives is used to catalyze the reaction; e.g. about 0.01-0.3 percent by weight of the reaction solution is suitable.

The temperature of the reaction can vary but it is generally preferred to conduct the reaction at a temperature between about 100 and 250 C. and typically between 175 and 225 C. The pressure can also vary but preferred pressures are autogenous pressures of at least one atmosphere.

Many of the carbonates produced by this reaction are well-known and are useful as synthetic lubricants, solvents and chemical intermediates. For example, diethyl carbonate is an intermediate in the production of phenobarbital. Many carbonates produced by this process are solvents for cellulosic compounds, e.g. cellulose nitrate.

DESCRIPTION OF SPECIFIC EMBODIMENT Several reactions were conducted in heavy-walled glass ampoules. The ampoules were purged with argon and charged with catalyst, hydroxy-containing compound and alkylene carbonate. The ampoules were then cooled and sealed in an argon atmosphere. After sealing, they were placed into a metal rocker bomb which was then pressur- 2 Reaction Temperature was 175 C.

We claim: 1. A process for making a carbonate having the formula which comprises contacting an alkylene carbonate having the formula with a non-tertiary hydroxy-containing compound having the formula R--OH while in the presence of a catalytic amount of an alkali metal or a basic derivative thereof wherein each R independently is alkyl or alkoxyalkyl and R is H, alkyl, alkoxy or alkoxyalkyl.

2. A process as described in claim 1 wherein the temperature is between about and 250 C.

3. A process as defined in claim 2 wherein a molar excess of hydroxy-containing compound is used.

4. A process as defined in claim 3 wherein each R has up to twelve carbon atoms and R has up to ten carbon atoms.

5. A process as defined in claim 1 wherein the temperature is between and 225 C.

6. A process as defined in claim 5 wherein the molar ratio of hydroxy-containing compound to alkylene carbonate is at least 2/ 1.

7. A process as defined in claim 6 wherein each R is 7 References Cited alkyl having up to six carbon atoms and R is H or alkyl UNITED STATES PATENTS havmg carbon amms' 2,915,529 12/1959 Bell et a1. 260-3402 8. A process as defined in claim 7 wherein the catalyst is an alkali metal, or a hydride, hydroxide, alcoholate, 5 3133113 5/1964 Malkemus 260463 amide or basic salt thereof.

9. A process as defined in claim 8 wherein the hydroxy- LEWIS GQTTS Primary Exammer containing compound is methanol or ethanol, the alkylene D. G. RIVERS, Assistant Examiner carbonate is ethylene carbonate or 1,2-propylene carbonate, the catalyst is sodium hydroxide or sodium car- 10 bonate and the pressure is antogenous. 25252 R 

